Equipment required for network operation. Equipment for the local network. A variety of network equipment

The computing network fragment (Fig. 1) includes the main types of communication equipment used today to form local networks and connect them through global connections with each other. To build local connections between computers, various types of cable systems, network adapters, repeaters, bridges, switches and routers are used. To connect local networks to global bonds, special outputs (WAN ports) of bridges and routers, as well as data transmission equipment for long lines - modems (when working on analog lines) or the device connection to digital channels (TA - ISDN terminal adapters, Digital dedicated channels of the CSU / DSU type channels, etc.).

Fig. one. Fragment of the network

The role of the cable system

To build local connections in computing networks, various types of cables are currently used - coaxial cable, cable based on shielded and unshielded twisted pair and fiber optic cable. The most popular type of data transfer environment for small distances (up to 100 m) becomes unshrange twisted parawhich is enabled in almost all modern standards and technology of local networks and provides bandwidth up to 100 MB / s (on Category 5 cables). Fiber optic cable It is widely used both to build local ties and for the formation of highways of global networks. The fiber optic cable can provide a very high channel bandwidth (up to several GB / s) and transmitting to considerable distances (up to several tens of kilometers without intermediate signal amplification).

An electromagnetic wave of different frequencies - KV, VHF, microwaves are also used as a data transmission environment in computing networks. However, while in local networks, radio communication is used only in cases where it is impossible to lay the cable laying, for example, in buildings that are architectural monuments. This is primarily due to the insufficient reliability of network technologies built on the use of electromagnetic radiation. To build global channels, this type of data transfer medium is widely used - it contains satellite communication channels and ground radio relay channels operating in direct visibility zones in microwave ranges.

According to foreign studies (LAN Technologies magazine), 70% of the downtime is due to problems resulting from the poor quality of the cable systems used. Therefore, it is so important to properly build the foundation of the network - the cable system. Recently, a structured cable system is increasingly used as such a reliable basis.

Structured cable system Structured Cabling System, SCS) is a set of switching elements (cables, connectors, connectors, cross panels and cabinets), as well as methods of their sharing, which allows you to create regular, easily expandable link structures in computing networks.

Advantages of a structured cable system:

• Universality. The structured cable system with a well-thought-out organization can become a single medium for transmitting computer data on a local computer network, organizing a local telephone network, transmission of video information and even transmitting signals from fire safety sensors or security systems. This allows you to automate many processes for monitoring, monitoring and managing economic services and livelihood systems.
• Increase service life. The aging period of a well-structured cable system can be 8-10 years.
• Reducing the cost of adding new users and changes to their placement places. The cost of the cable system is mainly determined by the cost of the cable, but the cost of work on its laying. Therefore, it is more advantageous to spend one-time work on the cable laying, possibly with a large margin in length than to perform the gasket, increasing the length of the cable. It helps to quickly and cheaply change the structure of the cable system when the personnel moves or the application change.
• The possibility of easy network expansion. The structured cable system is modular, so it is easy to build up, allowing you to easily and at the cost of low costs to switch to more advanced equipment that meets the growing requirements for communications systems.
• Ensuring more efficient maintenance. Structured cable system facilitates maintenance and troubleshooting compared to the tire cable system.
• Reliability. Structured cable system has increased reliability Since usually the production of all its components and technical support is carried out by one manufacturer.

Topology network

Topology, i.e. Configuration of the connection of elements in the LAN attracts attention to a greater extent than other network characteristics. This is due to the fact that it is the topology that determines many important properties of the network, for example, such as reliability (survivability), performance, etc.

There are different approaches to the classification of topologies of the LAN. According to one of them, the configuration of local networks is divided into two main classes: broadcast and consistent. In broadcast configurations, each PC (transceiver of physical signals) transmits signals that can be perceived by the rest of the PC. Such configurations include a common tire, wood, star with a passive center. In consecutive configurations, each physical sublayer transmits only one PC information. Hence it is clear that broadcast configurations are, as a rule, a LAN with a selection of information, and consistent - LANs with information routing.

In broadcast configurations, relatively powerful receivers and transmitters, which can work with cigals in a large level range. This problem is partially solved by the introduction of restrictions on the length of the cable segment and the number of connections or the use of digital repeaters (analog amplifiers).

Network topology is a geometric shape of the network. Depending on the topology of the connections of the nodes, the tire (trunk), ring, star, hierarchical, arbitrary structure is distinguished (Figure 3).

Figure 3 - Network topologies

Type Type Configuration is a more developed version of the tire type configuration. The tree is formed by connecting multiple tires with active repeaters or passive multiplayers ("hubs"). It has the necessary flexibility in order to cover several floors in the building or several buildings on one territory. In the presence of active repeaters, the failure of one segment does not lead to the failure of the rest. In case of refusal failure, the tree branches down to two subsection or two tires.

Broadband LAN with a type of wood configuration often have the so-called root - a control position in which the most important network components are placed. The reliability of this equipment is high demands, since it depends on the work of the entire network. For this reason, the equipment is often duplicated.

Another common way to connect subscriber systems in the LAN with their small number is a hierarchical connection. In it, intermediate nodes operate on the principle of "accuming and passing". The main advantages of this method are to the possibility of an optimal compound of the computer included in the network. Disadvantages are mainly related to the complexity of the logical and software structure of the LAN. In addition, such LANs decreases the rate of information transfer between subscribers of various hierarchical levels.

The most common consecutive configurations - "Ring", "chain", "Star with an intelligent center", "Snowflake". In the configurations "Ring" and "chain" for the proper functioning of the LAN, the constant work of all PMA blocks is necessary. To reduce this dependence, a relay is turned on into each of the blocks, blocking block when faulty. To simplify the development of the RMA and PC, the signals are usually transmitted over the ring only in one direction. Each LAN station has a memory of several bits to a whole package. The presence of memory slows down the data transmission in the ring and determines the delay, the duration of which depends on the number of stations. Returning back to the station - the sender, the sender during the package processing can set some confirmation indicator. This indicator can serve to control the flow and (or) acknowledgment, and should return to the source as quickly as possible. The flow control assumes the removal of packets from the rings by the recipient or after the complete circle is completed - the station - the sender. Since any station may fail and the package may not be asked, it is usually necessary for a special "garbage collector", which identifies and destroys such "lost" packages.

Network adapters

Network adapter (Network Interface Card, NIC) is a computer peripheral device directly interacting with a data transmission medium that directly or through other communication equipment connects it to other computers. This device solves the task of a reliable exchange of binary data represented by the corresponding electromagnetic signals, according to external communication lines. Like any computer controller, the network adapter runs running the operating system driver and the distribution of functions between the network adapter and the driver may vary from implementing the implementation.

In the first local networks, the network adapter with a coaxial cable segment was the entire spectrum of communication equipment, with which the interaction of computers was organized. The network adapter of the sender computer directly on the cable interacts with the recipient's network adapter. In most modern standards for local networks, it is assumed that a special communication device (hub, bridge, switch or router) is installed between network adapters of interacting computers, which takes some functions to control the data stream.

The network adapter usually performs the following functions:

• Registration of transmitted information as a frame form of a specific format. The frame includes several service fields, among which there is a destination computer address and the frame checksum on which the network adapter of the destination station makes conclusion about the correctness of the information delivered over the network.
• Get access to data transmission medium. In local networks, the communication channels (total bus, ring) are mainly used, access to which is provided by a special algorithm (the most frequently applied the random access method or method with the transmission of the access marker). In the latest standards and technology of local networks, there was a transition from using a shared data transmission environment to use individual computer link channels with network communication devices, as always was done in telephone networks, where the telephone apparatus is associated with the PBX-individual linte switch. Technologies using individual communication lines are 100VG-AnyLAN, ATM and commuting modifications of traditional technologies - Switching Ethernet, Switching token Ring and Switching FDDI. When using individual communication lines, the network adapter function often includes a connection with a network switcher.
• Coding the sequence of the frame bit by a sequence of electrical signals during data transmission and decoding when taken. Coding should provide the transmission of initial information on communication lines with a specific bandwidth and a certain level of interference so that the receiving party can recognize with a high degree of probability sent information. Since broadband cables are used in local networks, the network adapters do not use the signal modulation necessary to transmit discrete information from narrowband communication lines (for example, telephone channels of tone frequency), and transmit data using pulse signals. Representation of binary 1 and 0 may be different.
• Converting information from parallel shape to serial and back. This operation is related to the fact that to simplify the problem of synchronization of signals and reduce the cost of communication lines in computing networks, the information is transmitted in a sequential form, bit beyond the bit, and not tolerately, as inside the computer.
• Synchronization of bits, bytes and frames. For sustainable reception of the transmitted information, it is necessary to maintain the permanent synchronism of the receiver and the information transmitter. The network adapter uses special coding methods to solve this problem that do not use additional tires with clock sync signals. These methods provide a periodic change in the status of the transmitted signal, which is used by the tact generator of the receiver to adjust synchronism. In addition to synchronization at the bits level, the network adapter solves the task of synchronization and at the level of bytes, and at the framework of the framework.

Network adapters differ in the type and bit of the internal data bus used in the computer - ISA, EISA, PCI, MCA.

Network adapters also differ by type of network technology adopted in the network - Ethernet, token Ring, FDDI, etc. As a rule, the specific network adapter model works on a specific network technology (for example, Ethernet). Due to the fact that for each technology, it is possible to use various data media (the same Ethernet supports a coaxial cable, unshielded twisted pair and fiber optic cable), a network adapter can support both one and several media. In the case when the network adapter supports only one data transfer medium, and the other, transceivers and converters are used.

Transceiver (transceiver, trans.mitter + Re. ceiver.) - This is part of the network adapter, its terminal device leaving the cable. In the first Ethernet standard running on the thick coaxial, the transceiver was located directly on the cable and binds to the rest of the adapter located inside the computer, using the AUI interface (Attachment Unit Interface). In other Ethernet variants, "but it turned out to be convenient to release network adapters (and other communication devices) with the AUI port to which the transceiver can be attached for the desired environment.

Instead of selecting a suitable transceiver, you can use converterwhich can match the output of a transceiver intended for one environment, with a different data transfer medium (for example, a watery output is converted to an output to the coaxial cable).

Depending on the place and purpose of creating a local network, a variety of network equipment may be needed. At the same time, the modern equipment market for local computing networks is striking the novice administrators by the variety of prices and models, so here we will look at what will be needed to combine computers in a single knowledge.

Typical composition of the equipment of the local network

Network cables

There are several varieties of network cables for mounting a local network:

1. 1. Twisted steam is the most common (currently) cable type used to combine computers to the local network. The cable consists of eight copper wires that are connected in a strict sequence through the RJ-45 connector.

There are many varieties of this cable - depending on the brand and conductivity. Cat 6 Category Cable is very popular, in addition to good cable protection, high conductivity performance. The main disadvantage of creating a local network using a twisted pair is a relatively small distance between dots of connections (it should not exceed more than a hundred meters).

1. 2. Fiber optic cable.

The main advantage of this cable is a good data transfer rate. There are no restrictions on this connection in the distance, however, the cost of fiber is significantly higher than the "classic" twisted pair.

In addition, this cable requires a special soldering in places of compounds that only a specialist with special equipment can do

Network cards

As a rule, each computer is equipped with a network card. This is a device that allows you to send and receive data through network protocols.

There are two varieties of network cards:

1. 1. The built-in network card, has a board view that is inserted into a special jack on a personal computer. It includes the connector for the RJ 45 connector and the data processing processor. Unlike stationary computers, laptops and netbooks are already equipped with a network card built into the motherboard.
2. 2. The external network card is mainly supplied in the form of a USB-RJ45 adapter. It is used on many personal computers and laptops, which for some reason there is no possibility to install internal network cards.

Network switches

Special equipment that filters and enhances the network signal. The main advantage of switches is a traffic saving, since the switch sends a signal only to the network computers, ignoring the equipment off.

Switches are divided into several varieties depending on the following characteristics:

1. 1. Switch transfer rate - i.e. What speed will be sent network packets: 10, 100 or 1000 MB per second.
2. 2. Number of ports at the switch. Depending on the number of connected jobs, you can use the switch to 8.16 and 24 directs on your local network.

Routers (routers)

This equipment is mainly used to combine networks (such as Ethernet and WAN). And also filters routes for sending data to the built-in algorithm.

Network adapters

Network adapters, or network cards, are special devices, the main purpose of which is to provide bidirectional data exchange between the personal computer and the local network. As one of the components of the computer's hardware configuration, the same as, for example, a modem, a video adapter, or a sound card, network adapters are connected to a PC through one of the standard ports, and configured similarly to other equipment. Currently, it is customary to distinguish between several types of network adapters on the principle of the interface used as for. Compounds with a computer and for connecting a network cable.

Mono Interface and Combined Network Adapters

Today, the most common classes of local Ethernet networks are 10Base2 and 10Baset. The first are created on the basis of a coaxial cable, and therefore network adapters running with this type of networks are equipped with the Bayonet Network Connector connectors (BNC).

Figure 5 - BNC connector for local networks 10Base2

These connectors have a cylindrical shape and externally remotely resemble the receiving socket of the television antenna plug. On the outer surface of the cylindrical part of the connector, as a rule, there are two small protrusions with a height of approximately a millimeter intended for fixing the T-connector lock.

The second variation of network cards is designed to work with networks of class 10Baset and is completed with the RJ-45 connectors (Figure 6).

Figure 6 - RJ-45 connector for local networks 10Baset

This type of connectors is well known to the owners of modems, modern phones and fax machines - externally, it is very similar to the contact jacks of these devices to which the telephone line is connected. The RJ-45 connector has a view of a rectangular shape with a small groove for a network plug lock, in the lower part of the socket, there are eight contacts connecting with the corresponding pins of a network cable fork.

Network adapters equipped with a connector of only one type, for example, BNC or RJ-45, is called mono interface. There are also network cards on which both types of connectors are called - they are called combined.

The answer to the question of whether the network cards of which type should be purchased when designing a small local network, is obvious: combined adapters allow you to plan a network laying with greater flexibility when choosing various options - if necessary, you can easily replace vitu pair on a coaxial cable and On the contrary. For large modern local networks that must meet the criteria for high reliability and scalability, mono interface network adapters are fully suitable with the RJ-45 standard connector, since such networks relate, as a rule, to the 10BaseT class and do not use other network interfaces.

Network Adapters ISA, PCI and USB

Another criterion, according to which it is customary to classify network cards, implies the difference between all the adapters available on the modern market on a simple sign - namely, the port by which the network card connects to the computer. In total, there are three most widespread options, and the first one is the network adapters connected to the PC motherboard through the ISA bus (Figure 7).

Figure 7 - ISA network adapter

The main distinguishing feature of the network cards of this type, allowing to determine the possibility of connecting it to the ISA slot, which is called "on the eye", is the elongated lower part of the board, on which the contacts are located to connect to the port - the contact site on the PCI network adapters is noticeably shorter. ISA cards are both mono interface and combined.

The network adapters of this class are currently found more and less often, since most of the Maternative Configuration Motherboards no longer supports the ISA bus, which is currently "obsolete". This is connected with some technical characteristics of this standard. For example, ISA devices do not allow automatically redistributing hardware interrupts, as a result of which they often become culprits of equipment conflicts. That is why such network fees are now in stores are very cheap - just five to fifteen dollars. For the same reason, before purchasing a similar network adapter, make sure that the ISA slot is present on your computer's motherboard.

Network cards of another category are connected to the PCI bus. To date, they are most common because the PCI slot is available on the motherboards of all modern computers (Figure 8). Like the ISA network cards, the PCI adapters can be either equipped with the RJ-45 connector, or have a combined interface. You can attribute network adapters connected to the USB bus (Universal Serial Bus, Figure 9). Such network adapters are implemented as an external device connected to the USB port of the computer by means of a special cable and do not require individual power.

Almost all of them are focused on using 10Baset / 100Baset in local networks and equipped with an RJ-45 connector for twisted pair.

Figure 8 - PCI Network Adapter

Figure 9 - USB Network Adapter

Since USB network adapters appeared on sale relatively recently, at least compared to their predecessors that support ISA and PCI standards, their technical characteristics look much more attractive. These devices practically do not require configuration (except for the need to install the appropriate drivers), work fast enough.

Considering the various types of network cards, you should say a few words and about the so-called integrated network adapters. Some modern models of motherboards are mainly intended to install Intel Pentium and AMD Athlon processors, have a built-in 10Baset / Loobaset network adapter. A distinctive feature of such boards is the RJ-45 connector mounted on them. The integrated network adapter drivers are usually included in the delivery of the motherboard drivers. In principle, nothing prevents the user to disable the built-in network adapter in the configuration of the personal computer and use any other network card, such as a PCI or USB device.

Network cable

One of the most important components of any local network is a network cable through which the communications laying is performed. In this section, we will look at two types of network cable used in local networks of class 10Base2 and 10Baset.

Coaxial network cable is used in local networks of class 10Base2. It has a four-layer structure: two layers of the coaxial cable are made of conductor, two from the dielectric. The most inner layer is the conductive lived, in which the carrier signal is transmitted on the local network. There can be presented in the form of several woven fine conductors, or in the form of one thick copper wire, which is a more common option. The veins are covered with a dielectric film, on top of which is located the second conductive layer - the so-called screen protecting the line from foreign interference. The screen is made in the form of a metal wire braid, sometimes besides the braid internal insulating layer wrapped in a metal foil - such cables are called cables with double shielding. Cables are found with a quaternary screening: they consists of two layers of braid and two foil layers or two foil layers, braids and a thin metal mesh. Such cables have a greater thickness, have high rigidity in bends and are used mainly in rooms with a significant level of radio-electronic interference. In the electrical circuit diagram of network connectors, the screen plays the grounding role. The last, fourth dielectric layer is located on top of the screen, providing not only electromagnetic cable protection, but also its protection against external physical damage (Figure 10).

Figure 10 - Coaxial network cable:

1-- Central wire (conductive live); 2-- insulating layer of central wire; 3-- shielding layer ("screen"); 4-- Protective shell (external insulator)

There are several different types of coaxial cable used in local networks of class 10Base2. Their characteristics are shown in Table1.

For local networks, a thin coaxial cable with a wave resistance Z \u003d 50 Ohms is mainly used, in Table. 4.1 This type of cable is represented by families RG-58, RG-174, RG-178, as well as a cable of domestic production of RK-50. In the event that you have a coaxial cable with an unknown wave resistance, then you can measure the exact diameter of the internal conductive conductors, the diameter of the shielding layer, to find in the directory the value of the dielectric constant for the dielectric cable and calculate the magnitude of the wave resistance according to the following formula (Figure 11):

Figure 11 - calculation of the magnitude of the wave resistance of the coaxial cable where E is the dielectric constant, D is the diameter of the central wire, A D - the inner diameter of the screen

Table 1 - Characteristics of various types of coaxial cable

* PE - polyethylene; PPE - Polystoinoentylene; M - copper wire; Ml - copper tinned wire; MS - Copper Silver Plated Wire

Twisted para

Despite its name, the "twisted pair" network cable, used in the construction of 10BaseT networks, contains not one, but four pairs of conductors, sent relative to each other. Each pair is also spinning relative to other pairs of conductors (Figure 12).

Figure 12 - Cable "Twisted Couple"

In each of four pairs of conductors, in this type of cable, the "main" wire, which, according to tradition, is called from the time of becoming a telephone connection, is called "Ring", and the "optional" wire, called "TIP". Ring wire insulating coating has a monophonic color, TIP wire coating - white with strips of primary color. If, for example, Ring has a green color, then TIP in this pair will be white with green stripes.

In order for the installation and laying of computer networks, it was easier to distinguish one pair of conductors from another, the Ring wires of each of the four pairs are abandoned in their own color, with each pair for simplicity its sequence number from 1 to 4. Thus, among the existing 8 Cable Wires "Twisted Pair" Conductings You can select the conductors Ringl, Tipl, Ring2, TIP2, Ring3, Tip3 and Ring4, TIP4. Compliance with the colors of conductors. Pairs numbers in the "Twisted pair" cable are shown in Table 2.

Table 2 - Conductor Couples in Cable "Twisted Couple"

Based on this table, it can be easily understood that if the technical documentation comes to the TIP4 wire, it will be a white wire with brown stripes, if it is mentioned, say, the Ring2 wire, then this wire has an orange color. Now, if necessary, we are without any difficulty, we find the desired conductor, removing the "twisted pair" cable insulating coating.

Based on the functional characteristics, such as bandwidth and resistance to interference, various brand of cable "twisted pair" is customary to divide into several categories, information about which in accordance with international standards ISO / IEC 11801 and ANSI / EIA / TIA-568 is given in the table 3.

Table 4 - AWG

The category to which one or another "twisted pair" cable is usually indicated in its marking, which is printed by the factory method on the external insulation of the cable. The diameter of the "Twisted Couple" wire is taken to calculate according to the American AWG standard (American Wide Gauge), and the smaller the diameter, the greater the value of AWG. Compliance of the AWG values \u200b\u200bThe conductor's diameter in millimeters is shown in Table 4.

In local networks 10baset, it is used, as a rule, the "twisted pair" cable category 5 or 5+, the conductor diameter 22 or 24 AWG. In some situations, for example, when the local network is placed in rooms with a high level of electromagnetic interference, or it is necessary to increase the accuracy of the transmission of information by reducing crosspin in the cable, a shielded "twisted pair" is used. As a rule, the screen is made of metal foil. In this case, there are several different shielding options: each of the four pairs can be wrapped, plus all of them are protected from above the additional foil layer located under the outer insulation (STP cable), or inside the cable there is one common screen (FTP brand cable ).

Hubs, or hubs, are a central link in local networks of classes 10Baset and 100baset having a topology "Star". In fact, the hub is a multiport repeater, that is, its main functional task includes receiving data from computer hub connected to ports or other hubs, reform the signal simultaneously with its gain, and its further relay to other ports. In addition to RJ-45 connectors for 10BaseT networks, many hubs also have BNC ports, which allows you to connect 10Base2 segments to them or use a coaxial cable as a trunk, connecting several hubs in the chain. As a rule, one of the hub RJ-45 connectors has a wiring that allows you to attach it to other hubs: such a "multi-storey" connection of the hubs to each other is called the term cascading. This port is usually indicated by the inscription "IN", "UPLINK", "Cascading" or "Cross-Over". In some cases, there is a MDI / MDI-X switch next to this port, which allows you to enable port or to normal mode as needed, or into cascading mode. If the port is not equipped with a switch, but it is required to connect another computer to it (for example, if all other ports are busy), for this you can use the Cross-Over cable, usually used to connect two computers on the "point - point" " There are many different concentrator models: they all differ in the number of ports, bandwidth and other technical characteristics. The most inexpensive options for small local networks are just a few dozen dollars, while more advanced hubs can do you several hundred US dollars.

Figure 13 - Concentrator

Introduction

Evaluating the processes of the functioning of modern enterprises, it should be noted the tendency of the increasing use of computer technologies in production, as well as to manage the enterprise and technological processes. Depending on the nature of the production, the management can participate from one to the hundreds, and even hundreds of thousands of computers separated in space and connected by means of communication to the network.

The local computing network (LAN) is a system for sharing information and distributed data processing, covering a small territory within enterprises and organizations focused on collective use of non-working resources - hardware (network equipment), software and information.

Basic network equipment LAN: Cables with terminal receiving and transmitting equipment; Workstations - computers; Servers - more powerful computers; Network adapters - network cards; modems; concentrators; switches; Routers and bridges.

In the modern market of computer equipment and technology, LAN network equipment, including personal computers, is represented by a great multitude of different types, modifications, development of competing manufacturers. This class equipment is updated continuously, it becomes an objective need for 5-7 years, which creates an objective need for computer technologies and specialists associated with computing equipment, constantly monitor market fluctuations and carry out an analysis of the composition and characteristics of the LAN network equipment for any required current moment. . The topic is relevant. The above and personal interest was said as the author of the final qualifying work in the performance of the technical task on the modernization of the current LAN at the service trading enterprise LLC Torg-Service, where I passed the production practice, and determined the choice of the topic.

The subject of studies of final qualifying work - equipment of a local computing network (LAN).

The object of the study is the composition and characteristics of the LAN network equipment.

The purpose of the final qualifying work is the analysis of the composition and characteristics of the LAN network equipment.

The objectives of the study leak out of the goal:

Examine scientific literature on the problem under consideration.

Determine the structure and function of the model of a local computing network (LAN), an abstract network model, the development of network protocols.

Review and analysis of the composition and characteristics of the network equipment of the local computing network.

Survey LAN LLC "Torg-Service" and analyze network equipment in order to modernize the work of the network in the enterprise within the technical task.

Develop and implement in the production elements of network upgrading.

The local computing network is nothing without hardware, network equipment, which is a "support" network, without equipment communication tools between themselves and with a network server. Structured cable systems, universal data transmitting data in LAN; Server cabinets, connectors, crossbar panels are protocol independent equipment. All other equipment on its device and functions are significantly dependent on what specifically the protocol is implemented. The main one is network adapters (CA), hubs or hubs, bridges and switches as a means of logical network structuring, computers.

Research methods in graduation qualifying work are the analysis of scientific literature, systematization and integration of theoretical knowledge and practical skills.

The work consists of introduction, three chapters, conclusion, a list of sources used, the graphic part of the work is presented in applications.

1. Analysis of the composition and characteristics of network equipment LAN

.1 Characteristics of the subject area

The local computing network (LAN) is a system for exchanging information and distributed data processing, covering a small territory within enterprises and organizations focused on collective use of public resources - hardware, software and information.

The main task solved when creating local computer networks is to ensure the compatibility of electrical and mechanical characteristics and ensuring the compatibility of information support (programs and data) on the coding system and data format. The solution of this task refers to the standardization area and is based on the so-called OSI model (model of interaction of open systems - Model of Open System InterConnections). The OSI model was created on the basis of the technical proposals of the International Institute of ISO standards (International Standards Organization).

OSI network model (EMVOS), basic reference model of interaction of open systems (Open Systems InterConnection Basic Reference Model, 1978), - an abstract network model for communications and network protocols. It offers a look at the computer network from the point of view of measurements. Each measurement serves its part of the equipment interaction process. Thanks to such a structure, the joint work of network equipment and software becomes much easier and more transparent.

According to the OSI model, the architecture of computer networks should be considered at different levels (the total number of levels is up to seven). The topmost level is applied. At this level, the user interacts with the computing system. Lower level - physical. It provides an exchange of signals between devices. Data exchange in communication systems occurs by moving from top level to the lower, then transportation and, finally, reverse playback on the client's computer as a result of moving from the lower level to the top.

To provide the necessary compatibility on each of the seven possible levels of the computer network architecture, special standards are called protocols. They determine the nature of the hardware interaction of network components (hardware protocols) and the nature of the interaction of programs and data (program protocols). Physically, the protocol support functions are performed by hardware devices (interfaces) and software tools (protocol support programs). Programs that support protocols are also called protocols.

Each level of architecture is divided into two parts:

specification of services;

protocol specification.

The service specification determines which does the level, and the protocol specification - as it does, and each specific level can have more than one protocol.

Consider the functions performed by each software level:

The physical level is connected to the physical channel, so disconnecting from the channel, controlling the channel. The data transfer rate and the topology of the network is determined.

The lowest level of the model is designed directly to transmit data stream. Carries out the transmission of electrical or optical signals into the cable or radio-ether and, accordingly, their reception and conversion into data bits in accordance with the methods of digital signal encoding. In other words, interfaces between the network media and the network device.

The parameters defined at this level: the type of transmitting medium, the type of signal modulation, the levels of logical "0" and "1" and so on.

At this level, hubs (hubs) are operating, repeaters (repeaters) of the signal and media converters.

The functions of the physical layer are implemented on all devices connected to the network. On the computer, the physical layer function is performed by a network adapter or serial port. The physical level includes physical, electrical and mechanical interfaces between two systems. The physical layer defines such types of data transmission medium as fiber, twisted pair, coaxial cable, satellite data transmission channel, etc. The standard types of network interfaces relating to the physical level are: v.35, RS-232C, RS-485, RJ-11, RJ-45, AUI and BNC connectors.

The channel level adds an auxiliary symbols to the transmitted arrays and controls the correctness of the data transmitted. Here the transmitted information is divided into several packets or frames. Each package contains source and destination addresses, as well as error detection tools.

It is designed to ensure the interaction of networks at the physical level and control over errors that may occur. The data obtained from the physical layer is packed in the frames, checks for integrity if necessary, corrects errors (forms a repeated request of the damaged frame) and sends to the network level. The channel level can interact with one or more physical levels, controlling and managing this interaction.

The IEEE 802 Specification shares this level into two sublayers - Mac (Media Access Control) adjusts access to the shared physical environment, LLC (Logical Link Control) provides network level maintenance. At this level, switches are operating, bridges.

The network layer defines the information transfer route between networks, provides error processing, as well as controlling data streams. The main task of the network level is the data routing (data transmission between networks).

The level of the OSI network model is designed to determine the data transfer path. Responsible for the broadcast of logical addresses and names in the physical, determination of shortest routes, switching and routing, tracking problems and "congestion" on the network.

Network level protocols route data from the source to the recipient. At this level, the router (router) works.

The transport level binds lower levels (physical, channel, network) with upper levels that are implemented by software. This level shares data to form data on the network from their transfer tools. Here is the separation of information at a certain length and refineed the address of the destination.

The model level is designed to ensure reliable data transfer from the sender to the recipient. At the same time, the level of reliability may vary widely. There are many classes of transport level protocols, ranging from protocols that provide only the main transport functions (for example, data transmission functions without confirmation of reception), and ending with protocols that guarantee delivery to the destination of several data packets in the proper sequence, multiplexing multiplexes of data streams, provide The data flow control mechanism and ensure the accuracy of the received data.

The session level manages the communication sessions between two interactive users, determines the beginning and end of the communication session, time, duration, and communication session mode, synchronization points for intermediate control and recovery during data transmission; Restores the connection after errors during the communication session without data loss.

Examples: UDP is limited by the integrity control of the data integrity within one datagram, and does not exclude the possibility of losing the entire package, or duplicating packets, violating the procedure for obtaining data packets. TCP provides reliable continuous data transfer that eliminates data loss or violation of their arrival or duplication, can redistribute data, breaking large data portions into fragments and, on the contrary, gluing fragments in one package.

The Executive Level - manages the submission of data in the form necessary for the User Program, produces compression and decompression of data. The task of this level is to convert data when transmitting information to the format that is used in the information system. When receiving data, this level of data representing the reverse transformation.

This level is responsible for transforming protocols and encoding / decoding data. Application requests received from the application level, it converts to the transmission format over the network, and the data obtained from the network converts to the format that is clear applications. At this level, compression / unpacking or encoding / decoding data can be performed, as well as redirects requests to another network resource if they cannot be processed locally.

The level 6 (representations) of the OSI reference model is usually an intermediate protocol to convert information from adjacent levels. This allows you to exchange between applications on heterogeneous computer systems transparent for applications. Presentation level provides code formatting and conversion. Code formatting is used to guarantee the application for processing information that would have meaning for it. If necessary, this level can translate from one data format to another.

The view level is dealt not only with data formats and presentation, it is also engaged in data structures that are used by programs. Thus, level 6 provides the organization of data when sending them.

The application level interacts with application network programs serving files, and also performs computing, information and search engines, logical information transformations, mail messaging, etc. The main task of this level is to provide a convenient user interface.

The upper level of the model provides user-defined application applications. This level allows applications to use network services, such as:

remote access to files and databases

shipping email.

From the above, we can conclude:

At different levels, the exchange occurs by various units of information: bits, frames, packages, session messages, user messages.

1.2 Composition and assignment of network equipment as an object of research

The main equipment of the LAN is cables with terminal receiving and transmitting equipment, network adapters, modems, hubs, switches, routers, bridges, workstations (PC), servers. The easiest example of network equipment is a modem, or a modulator-demodulator. The modem is designed to receive an analog signal from the telephone line, which is processed (by the modem itself) and is transmitted to the computer as information that is clear to the computer. The computer processes the information received and as needed, displays the result on the monitor screen. Usually allocate active and passive network equipment.

Under active equipment, the equipment followed by some "intellectual" feature. That is, the router, switch (SVITCH), etc. are active network equipment (ASO). On the contrary - the repeater (repeater) and the hub (hub) are not ASO, since they simply repeat the electrical signal to increase the distance of the connection or topological branching and nothing "intellectual" is not. But managed switches belong to active network equipment, as they can be endowed with some "intellectual feature".

Under passive network equipment, equipment is implied not endowed with "intellectual" features. For example - cable system: cable (coaxial and twisted pair (UTP / STP)), plug / socket (RG58, RJ45, RJ11, GG45), repeater (repeater), patch panel, hub (hub), balun (BALUN) for coaxial cables (RG-58), etc. Also, the passive equipment include assembly wardrobes and racks, telecommunication cabinets. Mounting cabinets are divided into: typical, specialized and anti-vandal. By type of installation: wall and outdoor and others.

The most important network equipment that allows you to transmit data on the transmission medium is network adapters, or network cards (networks). Different types of networks are different network adapters. That they are adapters, that is, an equipment adapted to one or another transmission medium.

Network card, also known as network card, network adapter, Ethernet adapter, NIC (English. Network Interface Controller) - peripheral device that allows the computer to interact with other network devices. Currently, network boards are integrated into motherboards for convenience and cheapening the entire computer as a whole.

By constructive implementation, network boards are divided into:

internal - individual fees inserted into PCI, ISA or PCI-E slot;

external, connecting via USB or PCMCIA interface preferably used in laptops;

built in the motherboard.

On 10 megabit network cards for connecting to a local network, 3 types of connectors are used:

8p8c for twisted pair;

BNC is a connector for a thin coaxial cable;

15-pin transceiver connector for thick coaxial cable.

These connectors may be present in different combinations, sometimes even three immediately, but at any given moment only one of them works.

Next to the connector for twisted pair, one or more information LEDs that report on the presence of connection and transmission of information are installed.

One of the first mass network cards was the Novell series NE1000 / NE2000, as well as a lot in the late 1980s, there were Soviet clones of network cards with the BNC connector, which were produced with various Soviet computers and separately.

Network Interface Card (or Controller), Network and its driver implements the second, channel level of the open systems in the end node of the network computer. More precisely, in the pair operation system, the adapter and the driver performs only the functions of the physical and woofer, while the LLC level is usually implemented by the operating system module, one for all drivers and network adapters. Actually it should be in accordance with the IEEE 802 stack model model. For example, in Windows NT, the LLC level is implemented in the NDIS module, with all network adapter drivers, regardless of which technology is supported by the driver.

The network adapter, together with the driver, perform two operations: transmission and reception of the frame. The transmission of the frame from the computer to the cable consists of the stages listed below (some may be absent, depending on the accepted encoding methods):

Receiving LLC data frame through an inter-level interface together with MAC address information. Usually, the interaction between protocols inside the computer occurs through buffers located in RAM. Data for transmitting to the network is placed in these buffers with top-level protocols that extract them from the disk either from the memory file cache using the operating system input / output subsystem.

Registration of the MAC-level data frame, which is encapsulated by the LLC frame (with discarded flags 01111110), filling the destination addresses and source, calculate the checksum.

Formation of codes symbols when using redundant 4B / 5B codes. Scrambling codes to obtain a more uniform spectrum of signals. This stage is not used in all protocols - for example, Ethernet technology is 10 Mbps without it.

Issue signals to the cable in accordance with the received linear code - Manchester, NRZ1. MLT-3, etc.

Reception of the frame from the cable to the computer includes the following actions:

Reception from the signals cable encoding a bitstream.

Selection of signals against noise background. This operation can perform various specialized chips or DSP signaling processors. As a result, some bit sequence is formed in the adapter receiver, with a large degree of probability coinciding with the one that was sent by the transmitter.

If the data before being sent to the cable was subjected to scrambling, then they are skipped through the deslarler, after which the code icons sent to the transmitter are restored in the adapter.

Check the checksum of the frame. If it is incorrect, the frame is discarded, and the corresponding error code is transferred to the top, the LLC protocol is passed. If the checksum is correct, then the LLC frame is removed from the MAC and is transmitted through the inter-level interface to the top, the LLC protocol. The LLC frame is placed in the RAM buffer.

As an example of the classification of adapters, we use the approach of 3COM. The company 3Com believes that the Ethernet network adapters have passed three generations in their development.

In the network adapters of the first generation, the method of multi-frame buffering is used. In this case, the next frame is loaded from the computer's memory to the adapter buffer simultaneously with the transmission of the previous frame to the network. In the reception mode, after the adapter fully received one frame, it can start passing this frame from the buffer into the computer's memory simultaneously with the reception of another frame from the network.

In second generation network adapters, chips with a high degree of integration are widely used, which increases the reliability of adapters. In addition, the drivers of these adapters are based on standard specifications. The second generation adapters are usually shipped with drivers operating both in the NDIS standard (network driver interface specification) developed by 3COM and Microsoft and Approved IBM and in ODI Standard (open driver interface) developed by Novell.

In the third-generation network adapters (for them, the company 3COM refers its Etherlink III family adapters) a conveyor framework scheme is carried out. It lies in the fact that the processes of receiving the frame from the computer's RAM and its transfer to the network are combined over time. Thus, after the reception of several first bytes, their transfer begins. It is essential (by 25-55%) increases the performance of the chain "RAM - adapter - physical channel - adapter - RAM". Such a scheme is very sensitive to the starting threshold, that is, to the number of byte frame, which is loaded into the adapter buffer before starting the transfer to the network. The third-generation network adapter performs self-configuration of this parameter by analyzing the working medium, as well as by the method of calculating, without the participation of the network administrator. Self-adjustment provides the highest possible performance for a specific combination of the performance of the internal busbar, its interrupts and direct memory systems.

The third generation adapters are based on specialized integrated circuits (ASIC), which improves the performance and reliability of the adapter while reducing its value. 3Com called its Parlell Tasking conveyor conveyor technology technology, other companies also implemented similar schemes in their adapters. An increase in the performance of the "adapter memory" channel is very important to increase the productivity of the network as a whole, since the performance of a complex route for processing frames, including, for example, hubs, switches, routers, global communication channels, etc., is always determined by the performance of the slower element itself This route. Therefore, if the server's network adapter or client computer runs slowly, no quick switches will be able to increase the speed of the network.

Network adapters manufactured today can be attributed to the fourth generation. Modern adapters necessarily include ASIC, which performs the MAC function (Mac-Phy), the speed is developed up to 1 Gbit / s, and there is also a large number of high-level functions. The set of such functions may include support for the RMON remote monitoring agent, frame priority scheme, computer remote control functions, etc. In server versions of adapters, almost necessarily the presence of a powerful processor that unloads the central processor. An example of a fourth-generation network adapter can be the 3Com Fast Etherlink XL 10/100 adapter.

The cable is an electronic signal transmission element by wires. Any cables consist of metal veins (wires) that conduct electric current. The wire is a kind of electronic signal transmission medium. When installing the cable, you must adhere to the methods of the correct cable laying. The cable can not be bent under an acute angle (let the corner be round) to reduce the likelihood of micro-damage. Network equipment is very sensitive to such damage. You cannot be repeatedly bend and blends the cable. This also leads to a violation of its microstructure and, as a result, the data transfer rate will be lower than usual, and the network will more often fail.

In computer stores you can find cables that are already initially designed for small distances.

When installing wireless networks, only the presence on the PCI or PCMCIA slot computer on laptops, or the USB connector, where the network adapter itself is also connected. The fact is that the data transfer environment for wireless networks is radio communication. There is no longer necessary to stretch the wires.

Connectors, or how they are still very often called ports used when creating stationary cable computer networks, today, there are three types: RJ-11 connector, RJ-45 connector and BNC connector.

The RJ-11 connector is more famous as a connector for connecting the phone. The cable under such a standard consists of four wiring. Such connectors are used on telephone analog or digital ADSL modem. In the standard embodiment, only two wiring are used in the RJ-11 connector: those that are in the middle.

The RJ-45 connector is a standard widespread network connector used in modern network adapters and similar equipment, has eight contacts. The presence of it on the motherboard suggests that a network card is integrated into the motherboard. The user who has the opportunity will connect to the computer local network will not be much difficulty connecting to it through this port.

And finally, the BNC connector is currently practically not applied. Appeared in the 70s when computer networks were only created. It can be found on TVs, as this connector is used to connect the antenna cable to the TV. It was on such cables that computer networks were built before. Now there are practically no such networks. However, the cable is widely used in everyday life when the antenna is connected to the TV and in the broadcasting equipment, as well as when creating wireless computer networks (also for connecting antenna).

Such equipment include such elements of network equipment such as routers, decoders for satellite antennas and modems.

Router or router - a network device, based on information about network topology and certain rules that make up a network layer packet shipment (OSI level 3) between different network segments.

Typically, the router uses the recipient's address specified in the data packets, and determines the path to the routing table by which the data should be transmitted. If there is no route in the routing table for the address, the package is discarded.

There are other ways to determine the transfer route of packets when, for example, the sender's address used to the upper levels and other information contained in the headers of the network layer packets is used. Often, routers can broadcast the sender and recipient addresses, filtering a transit data flow based on certain rules in order to restrict access, encryption / decryption of transmitted data, etc.

Routers help reduce network load, thanks to its separation on the domains of collisions or broadcast domains, as well as by filtering packets. Basically, they are used to combine networks of different types, often incompatible by architecture and protocols, for example, to combine local Ethernet networks and WAN connections using XDSL, PPP, ATM, Frame Relay protocols, etc., often the router is used to provide access from local network in the global network. The Internet performs the transmission functions of addresses and a firewall.

The router can act as a specialized (hardware) device and a regular computer that performs the functions of the router. There are several software packages (in most cases based on the Linux kernel) with which you can turn the PC to a high-performance and multifunctional router, such as Quagga.

To combine cables, connectors, plugs and network equipment together, the tools are used that are the most necessary for any system administrator. Naturally tools can be more, but in our case we will consider only the most basic, without which it is impossible to work in any system administrator.

When creating large computing networks for any institutions, it is necessary that the system administrator be aware of the latest rates for network equipment, this is important when it is necessary to provide preliminary calculations for the equipment purchased for the network. The rates for equipment and other goods of the administrator should not worry, he assumes the role of a person who will be engaged solely by the creation of the computer network itself.

So, in the system administrator's toolkit includes: ticks RJ-45, a stationery knife, a set of "jacks" RJ-45, a transvelca (digital device), patch cord, length 1.0 - 1.5 meters, a set of bolts for mounting equipment in System case, universal screwdriver, calculator. And now in order about each element separately.

RJ-45 ticks: Used for crimping couples, their presence is required if you are going to install the network.

To build the simplest local network, it is enough to have network adapters and a cable of a suitable type. But even in this case, additional devices require, for example, signal repeaters that allow you to overcome the limitations to the maximum length of the cable segment.

The main function of the repeater (REPEATER) is a repetition of signals entering one of its ports on all other ports (Ethernet) or the following port in the logical ring (TOKEN Ring, FDDI) synchronously with origin signals. The repeater improves the electrical characteristics of the signals and their synchronization, and as a result, it appears to increase the distance between the most remote stations.

The multi-port repeater is often referred to as a hub (HUB, Concentrator), because this device implements not only the function of the repetition of signals, but also concentrates in one device the functions of combining computers to the network. Practically in all modern network standards, the hub is a mandatory network element that connects individual nodes to the network.

Cable segments that connect two computers or any two other network devices are called physical segments. Consequently, hub and repeaters are a means of physical network structuring.

Network hub or hub (Jarg. From English. HUB - Activity Center) - a network device intended for combining multiple Ethernet devices to a general network segment. Devices are connected using a twisted pair, coaxial cable or fiber. The term hub (hub) is also applicable to other data transfer technologies: USB, FireWire, etc.

The hub operates at the physical level of the OSI network model, repeats the signal coming to one port to all active ports. If the signal is received, the collision is simultaneously occurring at the same time, and the transmitted data frames are lost. Thus, all device connected to the concentrator are in the same collision domain. Hubs always work in half-cups when all connected Ethernet devices are separated by an access strip provided.

Many concentrator models have the simplest protection against an unnecessary number of collisions arising from one of the connected devices. In this case, they can isolate the port from the overall transmission medium. Tire segments based on twisted pair are much more stable in the operation of the segments on the coaxial cable, since in the first case each device can be isolated with a concentrator from the overall medium, and in the second case, several devices are connected using one cable segment, and, in the case of large quantities Collisions, the hub can isolate only the entire segment.

Recently, the hubs are rarely used, instead of them, switches are distributed - devices, devices operating at the OSI model and improving network performance by the logical selection of each connected device in a separate segment, the domain of the collision.

Denote the following characteristics of network concentrators:

Number of ports - connectors for connecting network lines, concentrators are usually produced with 4, 5, 6, 8, 16, 24 and 48 ports (most popular with 4, 8 and 16). Hubs with lots of ports are much more expensive. However, the hubs can be connected cascid to each other, increasing the number of port segment ports. Some for this provide special ports.

The data transfer rate is measured in Mbit / s, hubs with a speed of 10, 100 and 1000 are produced. In addition, hubs are mainly distributed with the possibility of changing the speed, are indicated as 10/100/1000 Mbps. The speed can switch both automatically and with jumpers or switches. Usually, if at least one device is attached to the hub at the lower range, it will transmit data to all ports at this speed.

The type of network media is usually a twisted pair or fiber, but there are hubs for other carriers, as well as mixed, for example, for a twisted pair and coaxial cable.

Workstations (PCs) are formed in the LAN based on personal computers (PCs) and are used to solve applied tasks, issuing requests to the network for maintenance, receiving the results of queries' satisfaction, exchange information with other workstations. The PC core is a PC, on which the configuration of the workstation depends.

Network servers are hardware-software systems that perform the distribution functions of network access resources distribution, but can work as regular computers.

The server is created on the basis of a powerful computer, much more powerful than computers of workstations.

In LCS there may be several different servers for managing network resources, however there is always one (or several) file server (server without data) to control the external storage devices (memory) of shared access and organization of distributed databases. In conclusion, it should be noted that in LAN, an important role in organizing the interaction of the network equipment described above belongs to a channel-level protocol, which is focused on a completely defined network topology.

1.3 Technologies and Protocols for the interaction of Hardware LAN

When organizing the interaction of network equipment LAN, an important role is given to the channel-level protocol.

However, in order for the channel level to cope with this task, the LAN structure must be quite specific, for example, the most popular channel-level protocol - Ethernet - is designed for parallel connecting all nodes of the network to the total tire for them - the segment of the coaxial cable. . The TKEN Ring protocol is also designed for a completely defined configuration of connections between computers - connection to the ring. Ring and IEEE 802.5 are the main examples of networks with marker transmission. Networks with a marker transmission move along a small data block called a marker. Owning this marker guarantees the right to transfer. If the node accepting the marker does not have information for sending, it simply recrets the marker to the next end station. Each station can hold the marker for a certain maximum time (by default - 10 ms).

Initially, the technology was developed by IBM in 1984. In 1985, the IEEE 802 Committee on the basis of this technology adopted the IEEE 802.5 standard. Recently, even in IBM products, the technologies of the Ethernet family are dominated, despite the fact that earlier the company used token Ring for a long time to build local networks.

Basically, technology is similar, but there are minor differences. Token Ring from IBM describes the Star topology when all computers are attached to one central device (MSAU MultiTation Access Unit (MSAU)), while IEEE 802.5 does not sharpen attention on topology. The annex B shows the differences between technology. Ring - the technology of a local computer network (LAN) ring with "marker access" - a local network protocol, which is located on a channel level (DLL) of the OSI model. . It uses a special three-bike frame called a marker that moves around the ring. The possession of the marker gives the right to the owner to transfer information on the carrier. The cadres of the ring network with marker access moves in the cycle.

Stations on the local computer network (LAN) token Ring are logically organized in the annular topology with data transmitted sequentially from one ring station to another with a control marker circulating around ring access control. This marker transmission mechanism is shared by ArcNet, marker bus, and FDDI, and has theoretical advantages over stochastic CSMA / CD Ethernet.

This technology offers an option to solve the problem of collisions, which occurs when the local network is operating. In Ethernet technology, such conflicts occur while simultaneously transmitting information to several workstations located within one segment, that is, using a common physical data channel.

If the station that owns the marker, there is information for the transmission, it captures the marker, it changes the one bit (as a result of which the marker turns into the sequence "The beginning of the data block"), complements the information that he wants to convey, and sends this information to the next Ring Network Station. When the information block circulates over the ring, there is no marker in the network (if only the ring does not provide "early release of the marker" - Early Token Release), so other stations wishing to convey the information are forced to expect. Consequently, in networks token Ring can not be conflicts. If an early release of the marker is provided, the new marker can be released after the data block is completed.

The information block circulates over the ring until it reaches the intended destination station, which copies the information for further processing. The information block continues to circulate by ring; It is finally removed after reaching the station, which fishes this unit. The sending station can check the returned block to make sure it has been viewed and then copied by the destination station.

Unlike CSMA / CD networks (for example, Ethernet) networks with marker transmission are deterministic networks. This means that you can calculate the maximum time, which will pass before any end station can be transmitted. This feature, as well as some reliability characteristics, make the network token Ring ideal for applications where the delay must be predictable and the stability of the network is important. Examples of such applications is the environment of automated stations on the factories. It is used as cheaper technology, gained distribution everywhere where there are responsible applications for which there is not so much speed as reliable delivery of information. Currently, the Ethernet for reliability is not inferior to Token Ring and significantly higher in performance.

In the past few years, there has been a movement to refuse to use in local networks of shared data transmission environments and the transition to mandatory use between the stations of active switches to which the end nodes are attached to individual communication lines. In pure form, this approach is offered in ATM technology (Asynchronous Transfer Mode), and a mixed approach that combines shared and individual data transmission environments is used in technology weighing traditional names with the Switching prefix (switching): Switching Ethernet, Switching token Ring, Switching FDDI .

But, despite the emergence of new technologies, the classical protocols of local networks Ethernet and Token Ring on forecasts of experts will be used everywhere else, at least 5 - 10 years, and therefore, knowledge of their parts is necessary for the successful use of modern communication equipment. (Fiber Distributed Data Interface) - Fiber Optical Interface on Distributed Data - Data Transmission Standard in the LAN, stretched at a distance of up to 200 kilometers. Standard is based on the TKEN Ring protocol. In addition to the large area, the FDDI network is able to support several thousand users.

It is recommended to use a fiber optic cable as a data transmission environment in the FDDI, but the copper cable can be used, in which case CDDI reduction (Copper Distributed Data Interface) is used. A diagram of a double ring is used as a topology, and the data in the rings are circulated in different directions. One ring is considered the main one, the information is transmitted in the usual state; The second - auxiliary, on it, data is transmitted in the event of a break on the first ring. To control the status of the ring uses a network marker, as in TKen Ring technology.

Since such duplication increases the reliability of the system, this standard is successfully used in the main communication channels.

The standard was developed in the mid-1980s by the National American Institute of Standards (ANSI) and received an ANSI X3T9.5.5.Ethernet number (IEEE802.3U, 100BASE-X) - a set of data transfer standards in computer networks, at a speed of up to 100 Mbps Unlike the usual Ethernet (10 Mbps).

Fast Ethernet technology is an evolutionary development of classical Ethernet technology.

The main advantages of FAST Ethernet technology are:

an increase in the bandwidth of the network segments up to 100 MB / C;

preservation of star-shaped network topology and support for traditional data transmission environments - twisted pair and fiber optic cable.

Ethernet technology implementation options are the following (Appendix B):

Base-T - any of the 100 megabit standards FAST Ethernet for twisted pair:

BASE-TX - using two pairs of cable conductors 5 categories or shielded twisted pair STP Type 1;

Base-T4 - on a four-paced CAT3 cable (and above) in half duplex; no longer used;

Base-T2 - on two CAT3 cable pairs; No longer used.

The length of the 100Base-T cable segment is limited to 100 meters (328 feet). In a typical configuration, 100Base-TX uses to transmit data on one pair of twisted (twisted) wires in each direction, providing up to 100 Mbps with bandwidth in each direction (duplex).

Base-FX is an option Fast Ethernet using a fiber optic cable. This standard uses a long-wavelength part of the spectrum (1300 nm) transmitted over two veins, one for receiving (Rx) and one for transmission (Tx). The length of the network segment can reach 400 meters (1,310 feet) in half duplex mode (with a guarantee of the detection of collisions) and two kilometers (6,600 feet) in full-duplex when using multimode fiber. Work at large distances is possible when using single-mode fiber. 100Base-FX is not compatible with 10Base-FL, 10 Mbps with a variant of the fiber.

Base-SX is a cheap 100Base-FX alternative using multimode fiber, as it uses cheaper shortwave optics. 100Base-SX can work at distances up to 300 meters (980 feet). 100Base-SX uses the same wavelength as 10Base-FL. Unlike 100Base-FX, it allows 100Base-SX to be back-compatible with 10Base-FL. Through the use of shorter waves (850 nm) and a small distance on which it can work, 100Base-SX uses less expensive optical components (LEDs (LED) instead of lasers). All this makes this standard attractive for those who upgrade the 10Base-FL network and those who do not need work at large distances.

Base-BX is an option Fast Ethernet over a single-liner fiber, a single mode fiber is used, along with a special multiplexer, which breaks the signal to transmitting and receiving waves.

Base-LX is 100 Mbps Ethernet variant using an optical cable. The maximum length of the segment of 15 kilometers in full-duplex mode by pair of single-mode optical fibers.

Base-LX WDM is 100 Mbps Ethernet variant using a fiber optic cable. The maximum length of the segment of 15 kilometers in full-duplex mode is one single-mode optical fiber at a wavelength of 1310 nm and 1550 nm. The interfaces are two species, the wavelength of the transmitter is distinguished and marked either by numbers (wavelength), or a single Latin letter A (1310) or B (1550). Only paired interfaces can work in a pair: on the one hand, the transmitter is 1310 nm, and on the other - by 1550 nm.

ATM technology has many attractive properties - a scalable data transfer rate of up to 10 GB / s; Excellent support for multimedia traffic and the ability to work both in local and global networks. . (Asynchronous Transfer Mode) - an asynchronous data transfer method - network high-performance switching and multiplexing technology based on data transmission in the form of fixed size cells (53 bytes), of which 5 bytes are used under the title. Unlike a synchronous data transmission method (STM - Synchronous Transfer Mode), ATM is better adapted to provide data services with a highly different or varying bit rate.

The network is based on the ATM switch and ATM router. Technology is implemented both in local and global networks. Joint transfer of various types of information, including video, voice.

Data cells used in ATM are less compared to data elements that are used in other technologies. A small, permanent cell size used in ATM allows you to:

transmit data according to the same physical channels, both at low and at high speeds;

work with constant and variable data streams;

integrate any kind of information: texts, speech, images, videos;

maintain point-to-point connections, point-set, set-set.

ATM technology assumes firewall on three levels.

To transfer data from the sender to the recipient, VC virtual channels are created on the ATM network (Virtual Circuit), which are two species:

permanent Virtual Channel, PVC (Permanent Virtual Circuit), which is created between two points and exists for a long time, even in the absence of data for transmission;

switched Virtual Channel, SVC (Switched Virtual Circuit), which is created between two points immediately before transferring data and breaks after the end of the communication session.

For routing in packages, the so-called package identifiers are used. They are two species:

VPI (Virtual Path Identificator) - Virtual path identifier (channel number)

VCI (Virtual Connect Identificator is a virtual connection identifier (connections number).

FDDI technology comparison results with Fast Ethernet and Token Ring technologies are presented in Appendix V.

All stations on the FDDI network are divided into several types according to the following features: end stations or hubs; According to an option to join the primary and secondary rings; By the number of MAC nodes and, accordingly, MAC addresses at one station.

If the station is attached only to the primary ring, then this option is called single connections - Single Attachment, SA. If the station is attached to the primary, and to the secondary rings, then this option is called double connections - Dual Attachment, DA.

Obviously, the station can use the properties of fault tolerance provided by the presence of two FDDi rings only when it is double connected. As can be seen from Figure 1, the reaction of stations on the cable break is to change the internal paths of transmitting information between the individual components of the station. A virtual network is called a group of network nodes, whose traffic, including broadcast, is completely isolated from other network nodes on the channel level. This means that the transfer of frames between different virtual segments on the basis of the address of the channel level is not possible, regardless of the type of address - unique, group or broadcast. At the same time, inside the virtual network, the frames are transmitted using the switching technology, that is, only the port that is associated with the address of the frame destination.

Figure 1 - Reconfiguration of dual connection stations when cable breakdown

When using the technology of virtual networks in switches, two tasks are solved at the same time:

increased performance in each of the virtual networks, since the switch transmits frames in such a network only the destination node;

network isolation from each other to manage user access rights and create protective barriers to broadcast storms.

To communicate virtual networks in the interms requires a network-level attraction. It can be implemented in a separate router, and can also work as part of the switch software.

There are several ways to build virtual networks:

Grouping ports;

Grouping of MAC addresses;

Use of labels in the additional frame field - Private Protocols and IEEE 802.1 Q / P specifications;

Lane Specification for ATM-Commitors;

Using a network level;

VLAN based on port grouping.

The study and analysis of the scientific and technical literature of the subject area of \u200b\u200bfinal qualifying work has shown that: the need to meet the growing requirements of industrialists to local computing networks contributes to the dynamic change in the appointment, composition, structure, network organization methods. This, in turn, requires the development and implementation of new and more advanced types of hardware of networks, as well as development in the dynamics of technology and protocols for the interaction of equipment used when creating computer computing networks.

I, as the author of the final qualifying work, passed a production practice at the service trading enterprise LLC Torg-Service. Working on a duty engineer for the maintenance of technical means of the local network, which has been in force in the enterprise, studied the advantages and disadvantages of the current equipment, was able to realize his knowledge when developing and implementing the technical assignment received from the enterprise, the technical task of the technical part of the modernization project in the enterprise in the local computing Networks »(Appendix and).

2. Survey and analysis of LAN LLC "Torg-Service" for the purpose of modernizing the network

Torg-Service is a private enterprise, which includes 4 manufacturing departments and an administrative and economic department with accounting.

The company in order to profit is engaged in the production and adaptation of media materials, advertising audio rollers; develops software products for broadcasting companies, promotional ideas, concerts, etc.; selling mortgage and components for computer, as well as consumables; PC sales and service.

Distributed local computing network such a multifunctional company was developed and implemented in 2006.

Over the past 5 years, the current LAN has been outdated, and does not suit the performers and management of the organization for the following reasons: the weak speed of the network server and workstations; rigid structure and functions of equipment included in LAN; Outdated network protocols.

For this objective reason, the need for the modernization of the currently operating local computer network (LAN) arose.

The modernization project in the enterprise of the LAN is carried out in order to:

inclusion, in addition to the current, new technological equipment for the diagnosis and testing of mortgage and components of the computer, testing of the working capacity of the PC;

replacement of system and basic server support for modern, more powerful;

connecting three mobile jobs to the central LAN server.

At the same time, to provide employees of the enterprise, according to qualifications and positions, prompt and high-quality access to LAN resources, and to the resources of the global Internet. It is necessary that the individual time for the use of LAN and Internet resources is automatically taken into account.

Types and volumes of work subject to implementation.

To conduct a survey of the current LAN in order to revise the equipment of the network, the operation of protocols, the organization and maintenance of databases, as well as the operation of the server.

Make a scheme of equipment supposed to implement an upgraded network, include three mobile jobs in the scheme.

Ensure a selection and installation of a modern operating system, administration programs and modern communication protocols of the network.

Conduct an experienced operation of the modernized LAN enterprise.

2.1 Structure of the enterprise and the active LAN

The Survey of the LAN Service Trading Enterprise LLC "Torg-Service" was carried out in the framework of the "Technical Task for the Technical Part of the Modernization Project in the Local Computing Register" (Appendix and), made it possible to draw the following conclusions:

The company currently consists of 4 manufacturing departments and an administrative and economic department, which includes accounting and garage. The company is located in the same building and on the same floor.

Functions and tasks of the departments are as follows:

the production department (production) is engaged in the production and adaptation of media mothers, sales of advertising audio conversion;

commercial department - sells sales and purchase of components, PCs, work with clients, accounting, statistics;

the technical department - ensures the work of the LAN, serves all technical and software;

the service center - works with the population, takes into PC repair, carries out a test of components and a PC for a commercial department;

At the moment, the management plans to expand the activity

enterprises, namely, a list of service services provided to the population in order to ensure self-sufficiency of the service center. The department acquired modern equipment Antec P183 for testing and diagnosing components and mortgage details of computer, diagnostics of the work of personal computers purchased for commercial purposes by the enterprise and received from the public to repair or implement.

The structural scheme of the operating in the enterprise LAN is presented in Figure G.1. (Appendix D).

The network structure running under Windows Server 2003 networks that combines 20 computers corresponds to the structure of information flows. Depending on network traffic, computers in the network are divided into groups (network segments). At the same time, computers are combined into a group of principle: if most of the messages generated by them are addressed to the computers of this group.

Different channel-level protocols for the formation of a single transport system belong to the 2nd generation, i.e. Provide information transmission between end nodes.

Routing packets on the network goes according to the topology of the star.

The rights of access to information are determined individually to employees of each department. Some part of the information is publicly available, and some part should only be available to users of a particular department.

All network users have access to both internal information resources of the organization and to the resources of the global Internet. Moreover, in this case, access rights are also appointed individually to employees of each department, depending on the functions assigned to them in the process of economic activity of the company. For example, part of the staff should have access to all services and resources of the Internet, and the part must have access only to email, for example, using only a specific set of available protocols for these purposes.

Accounting for the work of a particular performer and a particular department on the network and from the Internet is difficult, because All the time goes to the enterprise and is not automatically taken into account, who specifically and when information is provided. And this is the violation of the confidentiality of information and the consumption of time on the unreasonable production need to work in the Internet.

There is no need to divide the network to virtual segments, the network is built without using VLAN technology. Traffic Movement For all departments Transparent, delimitation of access rights to information resources is provided by software at Active Directory (Windows 2003 Server directory service)

Based on the survey of the current LAN in the enterprise and in fulfillment of the technical task, I, as the author of the final qualifying work, was determined by the range of tasks that need to be further solved in the final qualifying work:

Include in the existing LAN structure newly received in the service center equipment and a second dedicated server to manage the works of the service center. Network Services Organization (Services): DNS, Active Directory, DHCP, DNS, File Server, Terminal Server;

Organize uninterrupted nutrition of active network equipment,

servers, use the distributed uninterruptible power system. The battery life should be at least 7 minutes.

In addition to the standard configuration, it is necessary that the uninterruptible power supplies of the main communication center support the following additional features:

Provide UPS management via SNMP / Telnet / HTTP network (using any Web browser); Foreway completion of each server connected to the UPS in case of a complete discharge of the batteries.

The upgraded network still has to ensure the interaction of 20 personal computers. Cable infrastructure is built on the basis of one Main Communication Center.

The network must provide: storage and management of files, network printing; email, optimal collective work with information (databases); backup server files; Backing up network application files (email storage, databases).

The entire network requires one main communication center.

As active network equipment, use 3COM products, and the communication channel bandwidth with workstations should be at least 100 Mbps, it is necessary to highlight this bandwidth for each workstation (switched network).

The highway should provide a bandwidth of at least 33% of the maximum traffic center traffic.

It is necessary to ensure management, monitoring, collecting statistics from active network equipment. Equipment must be managed only in the main communication center.

Means of effective management of internal network traffic are not required, to manage external Internet traffic, it is necessary to implement the system on the "traffic inspector" platform.

To improve the level of fault tolerance of the network, it is necessary to reduce power supplies for the devices of active network equipment of the main communication center.

Provide a structured cable system, to communicate with servers it is necessary to use a unshielded twisted pair cable, to communicate with workplaces it is necessary to use a unshielded twisted pair cable.

At each workplace of the enterprise specialists, it is necessary to establish the ports of the cable system in an amount of equal to 2. Moreover, the exceeding the number of jobs above the number of personal computers should be at least 30%, the average distance from the communication center to the workplace is 45 m.

The number of central servers should be 1.

Table 1, contains the distribution of applications and users to servers.

Table 1 - Services and Customers

local computing network Modernization

6. Required main server configuration:

Processor Type: Server (Intel Xeon 5140)

Number of processors in server: 4

RAM size (RAM) server (MB): 4096

Required volume of disk space (TB): 2

Desired body type: Intel SC5299-E Server Housing

You need a device for backup data: SPIRE SPECTRUM II (1 TB)

The number of server communication lines should be 1

The communication line rate should be 100 Mbps

Uninterruptible power sources.

Based on the above tasks of modernization of the operating in the enterprise of the LAN, we proceed to the rationale for the choice of equipment and equipment for equipment.

2.2 Trends of promising development of equipment of the network

Over time, standards that allowed us to combine computers to local networks were gradually optimized, the bandwidth of communication channels increased, the software has evolved, the data transfer rate grew. Soon, local networks began to be used not only for shipping between multiple computer computers and various documents, but also to transmit multimedia information, such as sound and image. This opened the possibility of organizing inside the local network of video conferencing systems, which allowed users of such a system to communicate in real time "directly", physically in various premises, perform joint editing of texts and tables, arrange "virtual presentations". Already, computer video communication systems are widely used by large commercial enterprises, which serve to organize relations between various departments, in military complexes for rapid information transmission between several subscribers and entire divisions, and recently - and in home "desktop" systems, as a means Leisure organization. Among the advantages of the KBC, you can mention a relatively low cost of operation compared to other communication systems that currently existing today, their multifunctionality, comparative ease of use. In the process of work, the video conference subscribers will generally see on the screens of their interlocutor's image monitors and their own, which is necessary for the implementation of the visual monitoring of the established connection.

In recent years, a steady trend of rapprochement of local networks with corporate and global networks leads to a significant interpenetration of their technologies (for example, the Internet in local). This requires almost a complete replacement of hardware and software LAN software. In Annex B, the main differences between network devices are given.

Together with rapidly developing and in demand in all spheres of human activity, the development and production of hardware and software networks does not stand at the site.

The promising development of hardware, cables, adapters, routers, switches, concentrators and other network equipment is in the direction of increasing the speed of transmission and processing information, ensuring protection against unauthorized interference in the operation of the network and equipment.

It should be noted that at present, many manufacturers of network equipment at the design and production stage laid in their equipment the possibility of further improvement by updating the firmware (firmware).

By applying the latest Windows Server 2008 operating system in local networks, improved operations management utilities, connection stability, management of burial, extended filtering and search data, multiple selection, check records, export functions, good fault tolerance of customers. Windows Server 2008 provides the ability to protect files and folders on the NTFS volumes thanks to the encrypted EFS file system.

2.3 Justification of the choice of equipment to upgrade network

Now, when the main tasks are defined, once again briefly remember the characteristics of the most common network equipment and differences between them (Appendix B).

Ethernet repeaters, often called concentrators or hubs, simply transmit the received packages to all their ports regardless of the addressee.

Bridges function in accordance with the IEEE 802.1D standard. Like the Ethernet switches bridges do not depend on the protocol and transmit the port packets to which the addressee is connected. However, in contrast to most Ethernet switches, the bridges do not transmit package fragments when conflicts and error packages occur, since all packages are buffered before sending them to the destination port. Package buffers (Store-and-Forward) leads to a delay in comparison with switching on the fly. Bridges can provide performance equal to the bandwidth of the medium, but the internal locking slightly reduces the speed of their operation.

The operation of the routers depends on network protocols and is determined by the information connected with the information transmitted in the package. Like bridges, routers do not convey to the addressee fragments of packets in the occurrence of collisions. Routers save the package entirely in their memory before transferring it to the destination, therefore, when using routers, packets are transmitted with a delay. Routers can provide a bandwidth equal to the channel bandwidth, but they are characterized by the presence of internal lock. Unlike repeaters, bridges and switches, routers change all transmitted packets.

The final network equipment is the source and recipient of information transmitted over the network.

Some network equipment uses the term Loopback in the virtual interface used to control. Unlike the LOOPBACK interface, the LOOPBACK device does not communicate with itself.

The print server is a device that allows a group of wired and wireless network users to share the printer at home or in the office. It has a high-speed USB 2.0, LPT or COM port port for connecting the printer. As a rule, equipped with a 10 / 100Base Ethernet interface and is often a high-speed interface of 802.11g wireless networks. Supporting many network operating systems, gives a high level of flexibility and productivity to the print process. When choosing equipment for the computer network with me, as the author, it was decided to choose a 3COM company as a manufacturer.

I stopped my choice for 3Com thanks to good reviews about the equipment of this manufacturer, and also due to the fact that in the production of its equipment, they supply it with additional functions, technologies and propators of their own development. The peculiarity is that if you build a network solely on the active network equipment of the company 3Com, the reliability and efficiency of such network increases significantly. This is due to the fact that the equipment tests itself, as well as neighboring active nodes, while constantly maintaining topical relations among themselves. In the network with equipment 3Com increases speed due to the traffic sealing technology. SWITCH type hubs were selected as switching devices, as they not only transmit a package to the destination port, unlike hubs, which only copy the resulting package to all ports, but also enhance the signal. This avoids the effect of signal attenuation at remote areas of the network. In addition, the Switch device allows you to significantly unload the network from excess traffic, since, unlike the hubs, the resulting signal is transmitted strictly to the destination port, and not duplicated to all ports.

Equipment in the case of comprehensive construction of the "turnkey" network is better to acquire from one supplier, as:

First, equipment supplies will probably be one-time;

Secondly, you can count on significant discounts, purchasing equipment, which will maximize the system of building a new network;

Thirdly, you can count on the operational round-the-clock technical support of this equipment and increased deadlines for the warranty service, which will significantly reduce the total cost of the equipment.

Based on the terms of the technical task and complaining all the details with the representative of the supplier, which is also the official distributor of the company 3COM in Russia, I came to the choice of equipment.

Thus, a complete set of active and passive network equipment, with the exception of printers, were purchased for 65 048, 68 rubles. Despite the fact that when choosing, the equipment of the class is used above average, quite functional and high-quality, moreover, with a margin at the rate of + 30% to the existing working places, the project turned out to be relatively inexpensive even by the standards of today. It remains only to configure workstations after installing the network and connecting end network equipment. Below, Table 2 provides configuration of network user computers.

Table 2 - Computer network user network settings

The main gateway - the address of the computer, which is intended for organizing an access of computer network users to the Internet. Main-central server with the Microsoft Windows 2008 Server Enterprise Edition installed on it, installed on it by network services Active Directory, DNS Server , File Server, etc. In this case, it is indicated as a network parameter, since when entering the system, the client computer must have a working DNS server on the network capable of allowing host names on their network addresses, which also performs the domain controller functions. The main DNS server, if it is not simultaneously an online gateway, is able to resolve only the range of internal names. To serve customer requests outside the internal network, it is not in a state. The server is optional - in this case is simultaneously an online gateway and a proxy server of the organization. As a network parameter, the user computer is prescribed, as it is capable of allowing its requests to resolve names to external resources to the Internet.

After setting up the central server, the Internet gateway and client computers, the network is ready to work.

2.4 Prospects for the development of LAN LLC "Torg-Service"

Currently, the requirements of high reliability, fault tolerance, restability after failures, high throughput and load capacity, scalability, and improving other quality and quantitative characteristics that affect the performance as a separate assembly and the entire network as a separate assembly . With each following generation, these requirements are performed by hardware manufacturers. However, development does not end this, but only begins.

Manufacturers, in addition to supporting open common protocols in their equipment, also include technologies, algorithms and protocols of their own inventions that increase the functionality of the devices, their performance and open additional features for fine tuning and control such equipment.

Development implies not only the improvement of what is already there is, but also the production of what was not widely used before. Such a breakthrough in our century was the use of broadband wireless access to civilian purposes. Such technologies include: SDH network, PRL, WiMAX, BWA, Wi-Fi.

Despite the fact that the well-widespread and proven technologies X.25, Frame Relay, FDDI, ATM, Ethernet are more widespread, undoubtedly use in certain niches and wireless access technologies. Moreover, in some cases, only wireless technologies will be able to access there, where there will be no technical conditions for wired, or it will simply be a physical possibility, due to their restrictions, pave the cable.

Wi-Fi is a radio network that allows you to transmit information between the objects by radio waves (without wires). Wi-Fi Alliance is engaged in the development of standards in this area. The main advantage of Wi-Fi is to provide customers - "mobility", which is extremely convenient. The main minus is a vulnerability before attackers.

At the moment, three standards of 802.11a, 802.11b and 802.11g are represented in the Russian market.

11B - the equipment of this standard supports the transfer rate to 11 Mbps. Frequency - 2.4 GHz. Encryption - WEP. This standard has a continuation, the so-called 802.11b +. The main difference between 802.11b + from 802.11b is the speed. 802.11b + allows you to exchange data at speeds up to 22 Mbps.

11G is a more advanced standard, which has enhanced the degree of protection and data transfer rate of up to 54 Mbps. Frequency - 2.4 GHz. Encryption - WEP, WPA, WPA2. The main feature of the equipment of this standard is its backward compatibility with the 802.11b standard. Those, if the 802.11g standard network adapter was previously purchased, then you can absolutely confident that you can work with it in the 802.11b standard.

Both the above standard are currently allowed to use in the Russian Federation, which cannot be said about 802.11A.

11A - standard similar to 802.11g, but created for the possibility of simultaneously connecting a variety of customers. Those. This standard allows you to expand the density with respect to 802.11g. The second most significant difference is the frequency of radio wave - 5GHz. It is because of the frequency that this standard in the territory of the Russian Federation without special permission cannot be used. (English. Worldwide Interoperability for Microwave Access) - Telecommunication technology developed to provide universal wireless communication at large distances for a wide range of devices (from workstations and laptop computers to mobile phones). The technology is based on the IEEE 802.16 standard, which is also called Wireless MAN. The name "WiMAX" was created by WiMAX forum - an organization that was founded in June 2001 in order to promote and develop WiMAX technology. The forum describes WiMAX as "standard technology-based technology that provides high-speed wireless network access, alternately dedicated lines and DSLs. Combins to solve the following tasks:

Connecting Wi-Fi access points with each other and other Internet segments.

Providing wireless broadband access as an alternative to dedicated lines and DSL.

Providing high-speed data services and telecommunication services.

Creation of access points that are not tied to geographical location. It makes it possible to access the Internet at high speeds, with a much larger coating than with Wi-Fi networks. This allows you to use technology as "main channels", the continuation of which traditional DSL and allocated lines and local networks are. As a result, this approach allows you to create scalable high-speed networks within the framework of whole cities.

The problem of the last mile has always been an urgent task for communication. To date, many technologies of the last mile appeared, and before any telecommunications operator is the task of choosing technology that is optimally solving the task of delivery of any type of traffic to its subscribers. There is no universal solution to this task, each technology has its own scope, its advantages and disadvantages. The choice of this or that technological solution is influenced by a number of factors, including:

operator's strategy, the target audience, which is currently offered and planned to provide services,

the amount of investment in the development of the network and the period of their payback,

already available network infrastructure, resources to maintain it in a working condition,

the time required to launch the network and start the provision of services.

Each of these factors have their own weight, and the choice of this or that technology is taken taking into account all of them in aggregate. A simple and efficient model that allows you to quickly evaluate the economic parameters of the application of WiMAX technology.

Many telecommunication companies make large rates for using WiMAX to provide high-speed services. And there are several reasons.

Firstly, the technology of the 802.16 family will allow economically more efficient (compared to wired technologies) not only to provide access to the network to new customers, but also to expand the range of services and cover new hard-to-reach territories.

Secondly, wireless technology has many more easy to use than traditional wired channels. WiMAX and Wi-Fi network are easy to deploy and as needed easily scalable. This factor turns out to be very useful when it is necessary to deploy a large network in the shortest possible time. For example, WiMAX was used to provide access to the network survivors after the Tsunami, which occurred in December 2004 in Indonesia (ACEH). The entire communication infrastructure of the region was disabled and was required to promptly restore communication services for the entire region.

In the amount, all these advantages will reduce prices for the provision of high-speed Internet access services for both business structures and individuals.

2.5 Development and implementation of elements of upgrading network equipment LAN LLC "Torg-Service"

Newly obtained equipment, test stand Antec P183, is proposed to connect through a server that is highlighted from available computers in the service center. It should provide work within the service center and communication with the main LAN server. The selection stopped on a typical configuration of a PC running Windows XP, 2 GB RAM, 400 GB hard disk memory.

Studies have shown that in order to solve the tasks set in the technical task (Appendix A), and fulfill the requirements for the operating system (Appendix D), you must install the Windows Server 2008 operating system on the central LAN server.

The housing for the new server is equipped with powerful power supplies, additional fans, removable plugs and protective front panel. The Tower (Rack) (5U) housing is selected (5U), which has been certified by the manufacturing company motherboard.

The high-speed DVD-ROM drive will not only save time when installing OS and application software (software), but also will be extremely useful when working with a centralized reference system.

Since all workstations connected to the network will constantly access the server, one of its most important components is a productive 64-bit network card. It effectively manages an informational exchange, that is, has a coprocessor that takes on the main functions of the central processor for processing entering the data server.

To ensure additional reliability, two network cards used simultaneously. Windows Server 2008 is equipped with improved control utilities. Provides the ability to create sustainable compounds and management of "burial", extended filtering and data search, multiple selection, check records, export function. Server 2008 provides reliable protection of files and folders on volumes, provides network scalability.

Annex E is presented an option to upgrade the network at the request of the customer: inclusion in LAN for three mobile places (Appendix A). The organization of such a network model assumes the presence of a VPN server in the central office to which remote clients are connected. Remote clients can work at home, or using a portable computer, from any place of the planet, where there is access to the World Wide Web. This method of organizing a virtual network is advisable to apply in cases of geographically not associated access to employees to the local network of the organization through access to the Internet. Often providers create for their clients VPN connections for organizing access to Internet resources.

The so-called Extranet VPN, when access to the organization's customers is available through secure access channels, is gaining widespread due to the popularity of e-commerce. In this case, the possibilities for using a local network will be very trimmed for remote clients, in fact they will be limited to access to the company's resources that are needed when working with their customers, such as commercial offers, and VPN is used in this case to safely send confidential confidential data. Information security tools - encryption protocols are embedded in a remote access client computer.

The encapsulation of data on the PRTR protocol is by adding the GRE (Generic Routing Encapsulation) header and the IP header.

This network is a domain network running Windows Server 2008. The server has two network interfaces with IP addresses, internal for LAN 11.7.3.1 and external 191.168.0.2 for communication with the Internet. It should be noted that when designing networks, the VPN server is placed in the latter queue.

In Windows Server 2008, the server's VPN role is simply implemented enough.

In our case, there is an already formed network, with addresses described above. Next, you must configure the VPN server, as well as allow specific users to access the external network. On the local network there is an internal site to which we will try to access virtual elements into it.

Following the wizard prompts in Figure 2, set:

in the first step, the necessary parameters;

in the second step, select remote access (VPN or modem);

in the third step, we establish remote access via the Internet;

at the fourth step, specify the server interface connected to the Internet in our case, 191.168.0.2;

at the fifth step, we define a way to assign addresses to remote clients, in our case it will be automatically assigned addresses.

So, the VPN server is created, after the installers have done, go to the management of users of our domain. For employees who need remote access to the internal network of the organization, allow this the most access by setting the corresponding switch on the Incoming Calls tab (see Figure 3).

It should be remembered that for correct operation it is necessary that the installed firewall allow the protocols used by VPN.

Figure 2 - Screenshot of the Server Setup Wizard dialog box

The server part was finished, go to the creation of the client part of the network on a remote computer.

To create the client part of the LCS network (Figure 4) on a remote computer, it is necessary:

in the first step, start the network connections master;

in the second step, following the prompts, choose the item "Connect to the network in the workplace";

in the third step, "Connection to the LAN";

at the fourth step, we enter the connection name;

in the fifth step, select whether you should be previously connected to the Internet (if you connect from space with constant access, select "No", if you use, for example, a mobile phone as a modem, then you should select a presets for connecting to the Internet).

on the sixth step, enter the IP address of the server to which access is accomplished (see Figure 4);

in the last (seventh) step, properties are adjusted, as well as some points regarding the security and type of the created connection are adjusted.

Figure 3 - Screenshot Connecting Mobile User Addresses LAN

In conclusion, I would like to say that in fact the methods of using VPN are a lot. The method described in this final qualifying work is good in that it ensures the security of not only information that is transmitted, but also the connection itself.

Figure 4 - Screenshot "Wizard new connections"

Configuring remote access is complete, it's time to check its performance. Let's start traditionally, with all the favorite Ping team, just try to "propagate" any workstation from our upgraded local network (Figure 5).

Everything works fine, it remains to measure the performance of the created network. To do this, copy the file via a VPN connection, as well as without using it, on a VPN server. A 100 Mbps network will perform as a physical information environment, in this case the network bandwidth is not a limiting factor. So, copying a file with a size of 342 921 216 bytes took place 121 seconds. With the connection of VPN - 153 seconds. In general, the loss in copy time was 26%, which is naturally, since when transmitting information via VPN, additional overheads appear in the form of encryption / decryption data.

Figure 5 - Connection Check Results Window

In our case, the PPTP protocol was used, when using other types of time loss protocols will also vary. Currently, Microsoft recommends using the L2TP IPsec protocol with smart cards to ensure maximum protection when authenticating and transmitting information.

Accounting for access to the external environment (Internet) and internal LAN reserves are proposed to provide using the Specialized Software "Traffic Inspector". The program is installed on the LAN central server and allows you to manage traffic, statistics, and access to the access provided, and access to the external network is provided with the NAT protocol.

Below (in Figure 6) is a screenshot of the TRAFFIC INSPECTOR program. It should be concluded that the survey of the equipment of the equipment operating on LLC "TORG-SERVICE" LAN has been conducted and solved problems: the development of the upgraded network scheme, the inclusion of three mobile jobs in the scheme, a substantiation of choice and installation on the central server LANs of the modern operating system Windows Server 2008 , VPN Servers for implementing the LAN Modernized Network Scheme, carried out an experimental operation of the upgraded LAN network.

Figure 6 - TRAFFIC INSPECTOR Call Screenshot

Conclusion

In the final qualifying work in the study and analysis of the composition and characteristics of network equipment by systematizing and integrating the theoretical knowledge and conclusions of a practical examination of the local computing network of LLC "TORG-SERVICE" of the local computing network, the following:

It is shown that the structure (architecture) of the network model, technology and network elements interaction protocols is played by an important task in designing, operation and modernization of the LAN.

The role, composition and characteristics of network equipment as an object of research is shown and studied.

Installed, LLC "Torg-Service", like any other enterprise, is extremely interested in maintaining "its" LAN at the present level in order to conduct effective business.

The tendencies of the promising development of the composition and functions of network equipment, the prospects for technologies and equipment interaction protocols are analyzed.

A practical diagram of the modernization of the current LAN is proposed, with the rationale for the choice of network equipment and the operating system in order to fulfill the technical task of the network user, LLC Torg-Service.

The first chapter of the work shows that the network equipment of the local computing network, being an essential component of the network architecture, cannot be considered without equipment communication tools and with a network server.

Structured cable systems, universal data transmitting data in LAN; Server cabinets, connectors, crossbar panels are protocol independent equipment.

All other equipment on its device and functions are significantly dependent on what specifically the protocol is implemented. The main one is network adapters (CA), hubs or hubs, bridges and switches as a means of logical network structuring, computers.

Chapter 2 noted that many of the modern network equipment devices combine a whole set of functions. For example, a modern ADSL - modem, in addition to the communication function with an ISP provider, is able to perform the functions of the firewall (firewall), router and a simple network filter. At the same time, the cost of such a modem does not go beyond the cost of the average class modem.

If earlier the network administration was solved by a specially designed complex software, which was installed on computers, now it became possible through the use of modern compact design devices or in a format for mounting in a Rack-rack, which perfectly cope with solving certain tasks, whether vlan - Switches, Firewall Screens, Network Protection Equipment, Operator Class Equipment (Multiplexers, Interface Converters, Modular Switches, etc.).

In many cases, manufacturers still at the production stage laid in their equipment the possibility of improving by updating the built-in software (firmware). This allows you to significantly reduce the total cost of owning equipment, as it disappears the need for the next-generation equipment output to throw out the former device and buy a new one. It is enough just to download and install the update, and the device acquires additional functionality, support for new protocols and advanced work algorithms.

The access technologies are constantly developing, there are already a volatile number of solutions on the market for access to various technologies: wired and wireless. Moreover, it is absolutely optional that wired and wireless access technologies compete with each other. Each of them has its own niche, its own scope. On the contrary, in the case of constructing complex and extended systems, these technologies can be used in the complex, and often one of the technologies creates a backup access channel, which will work in case of refusal of the main channel.

The implementation of this chapter of the final qualifying work allowed me to find it possible to deal with the situation in the equipment market, with technologies that will be used in the future to build local computing networks. The main directions of the development of network equipment are as follows:

an increase in the bandwidth of communication channels;

an increase in the data transfer rate between ports in network devices;

extension of the total bandwidth;

reduction of delays in passing packets through ports of active equipment;

improvement of existing technology and data transfer protocols;

development of new prospective access technologies;

development of more convenient and modern means and network equipment management techniques.

In the practical part of WRC, chapter 3, the development and implementation of the modernization of network equipment of the current LAN on the service trading enterprise TORG-SERVICE LLC under the "Technical Officer to fulfill the technical part of the modernization project of the currently operating local computer network" is presented.

new equipment for testing mortgage and components and PCs are connected;

the Windows Server 2008 operating system is mounted, in return for Windows Server 2003;

three working mobile places were introduced into the LAN functioning scheme, for which the main north and computers of the mobile jobs were made and verifying the performance of the VPN server.

Glossary

List of sources used

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Introduction

Chapter I Theoretical Network Construction Basics

Topology of computer networks

The ring is a topology in which each computer is connected by the link lines only with two others: it only receives information from one, and only transmits the other. The Topology Ring is presented in Figure 1.

Figure 1 - Topology Ring

On each line, as in the case of a star, only one transmitter and one receiver works. This allows you to abandon the use of external terminators. The work in the ring network is that each computer relays (renews) the signal, that is, acts as a repeater, because the attenuation of the signal throughout the ring does not matter, it is important only attenuation between adjacent rings computers. There is no well-selected center in this case, all computers may be the same. However, quite often in the ring allocated a special subscriber who manages the exchange or controls the exchange. It is clear that the presence of such a manager of the subscriber reduces the reliability of the network, because its output immediately paralyzes the entire exchange.

Star - Basic Topology Computer Network (Figure 2), in which all network computers are attached to the central node (usually switch), forming a physical network segment.

Figure 2 - Star Topology

Such a network segment can function both separately and as part of a complex network topology (as a rule, "tree"). The whole exchange of information goes exclusively through a central computer, which is in such a way a very large load is assigned, so it cannot be engaged in anything else. As a rule, it is the central computer that is the most powerful, and it is precisely all the functions for the exchange management. No conflicts on the network with a topology star are in principle are impossible, because the management is fully centrally.

Tire - is a common cable (called bus or highway) to which all workstations are connected. At the ends of the cable there are terminators to prevent signal reflection. The topology of the tire is shown in Figure 3.

Figure 3 - Topology Tire

Network equipment

Network equipment - devices required for computer network operation, for example: router, switch, hub, patch panel, etc. You can select active and passive network equipment.

Active network equipment

Under this name implies the equipment followed by some "intellectual" feature. That is, the router, switch (switch), flexible multiplexer, etc. are active network equipment. On the contrary - the repeater (repeater)] and the hub (hub) are not ASO, since they simply repeat the electrical signal to increase the distance of the compound or topological branching and nothing "intellectual" is not repeated. But managed hubs refer to active network equipment, as they can be endowed with a certain "intellectual feature"

Passive network equipment

Passive equipment differs from active primarily by the fact that it does not eat directly from the power supply and transmits the signal without enhancing it. Under passive network equipment, equipment is implied not endowed with "intellectual" features. For example, a cable system: cable (coaxial and twisted pair), fork / outlet (RG58, RJ45, RJ11, GG45), repeater, patch panel, hub, baloon for coaxial cables (RG-58), etc. Also, Passive equipment include mounting cabinets and racks, telecommunication cabinets. Mounting cabinets are divided into typical, specialized and anti-vandal. By type of installation: wall, outdoor and others.

Basic network equipment

To main network equipment belong:

The server is a highlighted computer. The server is called a computer allocated from a group of personal computers (or workstations) to perform any service task without direct human participation. The server and the workstation may have the same hardware configuration, as they differ only to participate in their work of a person for the console.

Some service tasks can be performed on the workstation in parallel with the work of the user. This workstation is conventionally called the unrequited server.

The console (usually - monitor / keyboard / mouse) and the person's participation is necessary for servers only at the primary setup stage, with hardware and maintenance and control in emergency situations (standard, most servers are controlled remotely). For emergency situations, servers are usually provided with one console kit on a server group (with a switch, such as a KVM switch, or without any).

As a result of specialization (see below), the server solution can get a console in a simplified form (for example, communication port), or losing it at all (in this case, the primary setting and non-control control can be performed only through the network, and network settings can be reset in default status). The server is shown in Figure 4.

Figure 4 - Server

The modem (acronym, compiled from the words modulator and demodulator) - a device used in communication systems for physical interface of the information signal with the distribution environment where it cannot exist without adaptation.

The modem modulator modulates the carrier signal during data transmission, that is, it changes its characteristics according to changes in the input information signal, the demodulator changes the process when receiving data from the communication channel. The modem performs the function of the terminal line of the communication line. The formation of data for transmission and processing of the received data is carried out by T.N. Terminal equipment (a personal computer can act in his role).

Modems are widely used to communicate computers via telephone network (telephone modem), cable network (cable modem), radio waves (en: packet_radio, radio relay). Previously, modems were also used in cell phones (until digital data transmission methods were supplemented). The modem is presented in Figure 5.

Figure 5 - modem

Twisted pair (eng. Twisted pair) - a view of a communication cable, represents one or more pairs of insulated conductors twisted with each other (with a small number of turns per unit length) coated with a plastic shell.

Steering conductors are performed in order to increase the degree of communication between the conductors of the same pair (electromagnetic interference equally affect both pair wires) and the subsequent decrease in electromagnetic interference from external sources, as well as mutual filings when transmitting differential signals. To reduce the connection of individual pairs of cable (periodic convergence of conductors of various pairs) in UTP cables category 5 and above, the pair wires are twisted with a different step. Twisted pair is one of the components of modern structured cable systems. Used in telecommunications and computer networks as a physical signal transmission environment in many technologies, such as Ethernet, ArcNet and Token Ring. Currently, due to its cheapness and light in the installation, is the most common solution for building wired (cable) local networks.

The cable connects to the network devices using an 8P8C connector (which is erroneously called RJ45). Twisted pair is presented in Figure 6.

Figure 6 - twisted pair

Coaxial cable (from lat. Co - together and AXIS - axis, that is, "coaxial"), also known as coaxial (from the English COXIAL), is an electrical cable consisting of the central conductor and the screen located coaxially. Usually serves to transfer high-frequency signals. Invented and patented in 1880 by the British physicist Oliver Hevisayd. The coaxial cable is presented in Figure 7.

Figure 7 - Coaxial Cable

Optical fiber - thread from optically transparent material (glass, plastic) used to transfer light inside by means of full internal reflection.

Fiber optics - section of applied science and mechanical engineering, describing such fibers. Optical fiber cables are used in fiber-optic communication, allowing information to transmit information over long distances with a higher data transfer rate than in electronic communications. In some cases, they are also used when creating sensors. Optical fiber is presented in Figure 8.